Problem painting multiple textures on same object
It appears to be a bug in 2.72 versions. I created a simple scene of a cube with a bump and a color texture in 2.72b and then downloaded copies of 2.69, 2.70a, 2.71, 2.72, 2.72a, and a standalone zip of 2.72b. Everything works as it should up to 2.71. The problem showed up in 2.72 so I didn't even bother with the a and b versions. I've put in a ticket on the bug tracker at https://developer.blender.org/T42769 so if anyone is having the same issue they can track the issue there.